Field of the Invention
This invention relates to control of cardiac arrhythmias. More particularly, this invention relates to minimally invasive methods for modifying the effects of the autonomic nervous system on the heart by denervation of epicardial fat pads.
Description of the Related Art
Innervation of the heart by the parasympathetic nervous system has a marked influence on aspects of the heart rhythm, and inter alia on atrial fibrillation. Recent research has demonstrated that parasympathetic ganglia are located in discrete epicardial fat pads:
The RPV fat pad, situated at the junction of the right atrium (RA) and right pulmonary veins (RPV), provides direct vagal inhibition of the sinoatrial (SA) node.
The IVC-ILA fat pad, situated at the junction of the inferior vena cava (IVC) and the inferior left atrium (ILA), selectively innervate the atrioventricular (AV) nodal region and regulate AV conduction.
The SVC-AO fat pad, situated between the medial superior vena cava (SVC) and aortic root superior to the right pulmonary artery, connects to vagal fibers projecting to both atria and to the IVC-ILA and PV fat pads.
It is known that individuals having a high level of vagal tone are predisposed to supraventricular arrhythmias, particularly atrial fibrillation. Ablation of epicardial fat pads has been found to affect vagally mediated atrial fibrillation. For example, in the document Catheter Ablation of Cardiac Autonomic Nerves for Prevention of Vagal Atrial Fibrillation, Jackman et al., Circulation 2000; 102:2774-2780, transvascular radiofrequency (RF) ablation of cardiac autonomic nerves for prevention of vagal atrial fibrillation in dogs is described, using an ablation catheter in the right pulmonary artery and or superior or inferior vena cava. A catheter that can be used for this purpose is described in commonly assigned U.S. Pat. No. 6,292,695 to Webster et al, which is herein incorporated by reference.
Surgical denervation of the fat pads has also been described.
The methods of parasympathetic denervation that are described in the literature generally involve surgical or transvascular approaches. There remains a need for improved, less invasive methods of denervating epicardial cardiac fat pads for prevention and treatment of supraventricular arrhythmias.